Chaos

Chaos is a "Second-Generation Angeloid, Type Epsilon" (第二世代エンジェロイドタイプε) and the first major antagonist introduced after the Master of Synapse.

She is ironically the most miniature and child-like Angeloid. Because of her nun-like garments, she has the abilility to manipulate her appearance through elaborated illusions, mimicking someone dear to her victim in order to instill turmoil and confusion (as her name implies), as she did against Nymph by taking on the form of Tomoki. She doesn't have wings like the other Angeloids, instead sporting a wicked array of bladed, organic-like appendages which act as an offensive weapon. What is most eerie about her is her strange obsession with love, having asked to Tomoki, Nymph, Astraea and Ikaros, often in an extremely creepy manner, what love is, to which Ikaros responded that love, for her, was a sensation of pain in her reactor, obviously in a figurative sense.

Chaos first appeared to torture Nymph and then fought Ikaros, whom she initially bested through her illusions. She battled Ikaros again, though this time the latter saw through her illusions and defeated her, sending Chaos into a deep abyssal chasm where she was temporarily incapacitated due to the great water pressure. While there, she wondered about Ikaros ' statement to what love means, coming to a dreadful conclusion: love equals to pain. Chaos was left in the abyss, dismembering and devouring fish to—in her own words, grow bigger—and show her "love" to everyone. But after the battle in episode 11 (forte), Chaos felt the same way when Ikaros was in love (When Ikaros's reactor hurt), this may indicate that she has also fallen in love with Tomoki.

Note: In the manga she has not shown her adult form so far but may show it later on.